ISL54065EVAL1Z Datasheet ISL54065EVAL1Z | P1-P3

AN1370.0

ISL54065EVAL1Z Evaluation Board

User’s Manual

Description

The ISL54065EVAL1Z evaluation board is designed to

provide a quick and easy method for evaluating the

ISL54065 IC.

The ISL54065 IC is a single supply Dual Single-Pole Double

Throw (SPDT) analog switch with negative swing capability,

sub-Ω ON-resistance and low power dissipation. The

ISL54065 is designed for applications that require an analog

switch that may see voltages below ground at the switch

terminals, such as audio and video. The ISL54065EVAL1Z

evaluation board is developed to evaluate the ISL54065 IC,

integrating many features for ease of use in examining the

performance of the device under various operating

conditions. To help understand the operation of the

ISL54065 IC and the ISL54065EVAL1Z evaluation board, it

is recommended to study the Evaluation Board Schematic

on page 5 of this application note, and refer to the datasheet

for the ISL54065 IC.

The ISL54065 IC is a dual SPDT analog switch that is

capable of swinging down to 6.5V below the positive supply

rail. For example, if the supply is at +1.8V, the switch

terminal analog operating range is from -4.3V to +1.8V. The

ISL54065 also integrates Click and Pop Elimination Circuitry

to remove transient noises at the speaker during power

ON/OFF of an audio system. The evaluation board contains

standard RCA/BNC connectors and a single headphone jack

to allow the user to easily interface with the IC to evaluate its

functions, features, and performance. The evaluation board

has selectable output loads of 20kΩ

and 32Ω resistors to

simulate an audio amplifier pre-amp or stereo headphones.

The board also has DC blocking capacitors at the switch

input to remove the DC bias of single supply amplifiers.

This application note will guide the user through the process

of configuring and using the evaluation board to evaluate the

ISL54065 device.

Key Features

• Selectable Output Resistive Loads and Input DC Blocking

Capacitors

• RCA Audio Input/Output Jacks, Stereo Headphone Output

Jack and BNC Connectors

• Convenient Test Points and Connections for Test

Equipment

• Click and Pop Elimination Circuitry

• Manual or External Logic Input Control

Picture of Evaluation Board (Top View)

Board Architecture/Layout

Basic Layout of Evaluation Board

A picture of the evaluation board is located in Figure 1. The

ISL54065 IC is soldered onto a 12 Ld wide DIP header

board. The DIP header board is mounted to the center of the

evaluation board. The evaluation board integrates the

necessary connections and components to interface with the

ISL54065 for ease of operation.

Power Supply

The ISL54065 IC requires a supply voltage in the range of

+1.8V to +6.5V for proper operation. Banana jacks for V

(J1) and GND (J2) are located at the top of the board. The

evaluation board contains a 10µF bulk capacitor and a 0.1µF

high frequency decoupling capacitor at the supply lines.

Logic Control

The evaluation board contains two types of logic control to

the digital logic inputs of the ISL54065 IC available to the

user. The logic pins can be controlled either through manual

or external operation. The logic control pins are manually

toggled by the SPST switches mounted on the evaluation

board (S1-S3). When the switch is in the up position (H) the

associated logic pin is pulled to V

for logic HIGH. When

the switch is in the down position (L) the associated logic pin

is pulled to GND for logic LOW. For manual operation, the

jumpers JP5-JP8 need to be in the 1-2 position.

Note: When JP6 is in the 1-2 position, the CP pin is

automatically logic HIGH.

For external control via a function generator or switched

source, set the jumpers JP5-JP8 in the 2-3 position. This

FIGURE 1. ISL54065EVAL1Z EVALUATION BOARD

Application Note February 3, 2009

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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AN1370.0

February 3, 2009

by-passes the SPST switches and routes the logic control to

the BNC connectors (J11-J14 located on the right side of the

board).

Note:S2 and S3 have a 3.9MΩ pull-down resistor hard-wired

from the INx pin to GND. These resistors do not appear on

the ISL54065EVAL1Z Board Schematic on page 5.

Switch Terminals

The evaluation board contains components to interface with

all six terminals of the Dual SPDT switch. The common

(COM) terminals of the switch are located in the upper right

section of the evaluation board. The Normally Open (NO)

and Normally Closed (NC) terminals of the switch are

located on the left side of the evaluation board. All switch

terminals include both RCA jacks and BNC connectors. The

COM terminals also include a headphone jack (HJ1) for

connecting a stereo headphone or line level plug.

Refer to Table 1 for a list of the pins on the ISL54065 IC and

the associated components on the evaluation board. The

evaluation board also includes Test Points for convenient

locations to probe specific pins on the IC.

TABLE 1. BOARD COMPONENT TABLE

Note: The audio inputs (NCx and NOx) have a 200µF series

DC blocking capacitance that can be used for AC coupling

audio signals that are DC biased in single supply systems. If

the audio source is not DC biased or if the audio source

already has a DC blocking capacitor, it is recommended to

bypass the capacitors (C3-C10) by placing jumpers on

JP1-JP4. The capacitance can be reduced to 100µF by

depopulating the 0

Ω resistor on R1-R4.

The audio outputs (COM1 and COM2) have selectable

output loads on the evaluation board. Jumpers JP9 and

JP10 configure the output load resistance. When the

jumpers are in the 1-2 position, the load impedance is 32Ω.

When the jumpers are in the 2-3 position, the load

impedance is 20kΩ. If the user decides to have no load

impedance on the evaluation board, simply remove the

jumpers.

Power Supply

The DC power supply connected at banana jacks J1 (VCC)

and J2 (GND) provides power to the evaluation board. The

evaluation board requires a +1.8V to +6.5V DC power

supply for proper operation. The power supply should be

capable of delivering 100µA of current.

Logic Control

The state of the ISL54065 device is determined by the Truth

Table as defined in the ISL54065 datasheet. When in

manual operation mode, the logic being toggled by the

SPST switches (S1-S3) will always drive the voltage of the

logic pin to V

for a HIGH and GND for a LOW. In external

control mode, the voltages being driven by an external

source must meet appropriate V

and V

levels as defined

in the datasheet.

The control pins are 1.8V logic compatible up to a +3.3V

supply, which allows for control via a standard µcontroller.

Logic “0” (LOW) when ≤ 0.5V

Logic “1” (HIGH) when ≥ 1.4V

When operating above +3.3V supply, refer to the datasheet

for appropriate logic levels to drive the logic pins. It is always

recommended to drive the logic pins to the positive supply

rail (V

) and GND to minimize power consumption.

Logic States

INPUT SELECT (INX) PINS

If the INx Pins are logic “HIGH”, then the NOx switches are

turned ON and the NCx switches are turned OFF. If the INx

Pins are logic “LOW”, then the NCx switches are turned ON,

and the NCx switches are turned OFF.

ENABLE (EN) PIN

If the EN Pin is logic “HIGH” the switches are active and their

logic state dependent on the INx pins. If the EN Pin is logic

“LOW”, both COMx terminals are turned OFF from the NCx

and NOx switch terminals. The part is disabled and no

signals will pass through the switch.

CLICK AND POP (CP) PIN

If the CP Pin is logic “HIGH”, shunt resistors are activated on

the NOx and NCx terminals to ground when the switch is

OFF. For example, if INx is logic “HIGH”, the NCx switches

are turned OFF. There will be a shunt resistance from the

NCx to ground. The value of this resistor is dependent on

supply voltage, but is typically 140Ω with a 3.3V supply.

Driving the CP pin logic “LOW” will deactivate the Click and

Pop Elimination Circuitry and there will be no active shunt

resistors on the switch terminals when a switch is turned

OFF.

ISL54065 PIN

EVALUATION BOARD

CONNECTION TEST POINT

VCC J1 TP1

GND J2 TP2

EN S1, J11 TP7

CP J12 TP8

IN1 S2, J13 TP9

IN2 S3, J14 TP10

NO1 J3, J4 TP3

NC1 J5, J6 TP4

COM1 J15, J16, HJ1 TP11

NO2 J9, J10 TP6

NC2 J7, J8 TP5

COM2 J17, J18, HJ1 TP12

Application Note 1370

AN1370.0

February 3, 2009

Note: If the CP is logic “HIGH”, and EN is logic “LOW”, the

NCx and the NOx switch terminals will have the Click and

Pop Elimination Circuitry active. Under this scenario, both

switch terminals with have a shunt resistor to ground.

CLICK AND POP OPERATION

Single supply audio sources are biased at a DC offset that

generates transients during power ON/OFF of the audio

source. This DC offset is coupled through a blocking

capacitor that is needed to remove the DC bias to the

speaker, causing a transient voltage at the load. For

example, when the source is OFF and suddenly turned ON

with a DC offset, the capacitor will develop a voltage equal to

the DC offset. If the ISL54065 does not have the Click and

Pop Elimination Circuitry active, a transient discharge will

occur in the speaker, generating a Click and Pop noise.

For proper operation of Click and Pop elimination, the switch

terminal that is being connected to the speaker should be

connected through the shunt resistor before connecting to

the load. This allows any transients generated by the source

to be discharged through the shunt resistor first, eliminating

any audible click and pop noises. With a typical DC blocking

capacitor of 200µF and the shunt resistance having a typical

value of 140Ω, allowing a 250ms dead time in for

discharging a transient will eliminate the click and pop noise.

Applications

The ISL54065 is designed to be a Dual SPDT switch for

multiplexing or switching of signals that require low insertion

loss, low power consumption, and negative voltage swing

capability. Such applications include Audio/Video equipment,

battery or portable devices and medical equipment. In

addition, the Click and Pop Elimination Circuitry makes it

ideal for portable audio such as MP3 players and cell

phones.

FIGURE 2. BASIC EVALUATION TEST SETUP BLOCK DIAGRAM

+1.8V TO +6.5V

DC POWER

SUPPLY

AUDIO SOURCE

SIGNAL

LEFT

RIGHT

LOGIC CONTROL

AUDIO SIGNAL

OSCILLOSCOPE

CHA

CHB

Application Note 1370

P1-P3 P4-P5

ISL54065EVAL1Z

Mfr. #:

Buy ISL54065EVAL1Z

Manufacturer:

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